KR Webzine Vol.138

The speed and power performance of a ship is not only a guarantee issue between the ship owner and the ship yard, it is also a key element covered by the Energy Efficiency Design Index (EEDI) regulation. Recently, the International Organization for Standardization (ISO) published procedures for the measurement and assessment of ship speed and power during sea trials. The results of any speed and power performance measurement in actual sea conditions must inevitably include various uncertainty factors.

Figure 1 Schematic of Monte Carlo method for uncertainty propagation

Influences for systematic error of shaft power measurement system was examined using Monte Carlo simulation. It was found that the expanded uncertainty of speed and power performance is about ±1.2% at the 95% confidence level (k=2) and most of the uncertainty factor is attributed to the shaft torque measurement system.

Figure 2 Uncertainty sources in sea trial